Why Energy Models?

09/22/2017

Built Green 4-Star project by Denizen Development LLC

Most builders pursuing Built Green certification quickly realize that the energy model of their project is one of the keys to achieving a given star-level. Almost all Built Green star-levels for nearly all certification types (Community certification and Refit certification being the exceptions) require an energy model.

How does this work? Why is this the case? Let us explain.

What is an energy model?

An energy model is a projection of how much energy a home will use, given its design and equipment. Energy models are extensively researched and widely accepted, but they are also an estimate of how much energy a home will use. There is no way to account for certain variables, occupant behavior being a big one. However, models can be very useful tools for judging a home’s efficiency and for comparing the likely benefits of different efficiency strategies.

There are many ways to perform an energy model and models may vary in their intricacy, in part due to different software tools that can be used. Built Green’s modeling protocol is based on the software REM/Rate for single-family models and on eQuest for larger, multifamily models.

Built Green’s… modeling protocol?

Yes, Built Green has a modeling protocol to ensure that projects are all being modeled the same way. On top of the different modeling tools, modeling is not an exact science and two different modelers could make two different decisions in how to account for certain components, with neither necessarily incorrect. To standardize our process and make sure that Built Green certification means the same thing for different projects, Built Green introduced modeling protocols to guide third-party verifiers and modeling experts. The protocols are designed with the input of experts and with the aim of making Built Green as accessible as possible for builders, while at the same time ensuring Built Green qualifies for various incentives. Third-party verifiers are a great resource for questions about modeling since they are the ones who often do the model or who work with the person doing the model.

So why a model?

Built Green is a certification that represents a building’s environmental gains above code. One of these gains is energy efficiency. Thus, projects need to demonstrate to Built Green that their energy consumption will be less than a similar code home and Built Green needs to demonstrate to governments and utilities that offer green building incentives that the program is meeting expectations. A model does just that.

What does the model show exactly?

Since Built Green is a regional certification, we look at improvement beyond the Washington State Energy Code. Models, therefore, show the percentage improvement of a Built Green home over its performance had it only been built to code. In other words, a model shows how much energy a home would use with code-compliant design and equipment and how much energy it would use as actually designed—the difference between the two being the energy reduction achieved by green upgrades and smart design. Built Green requires a 10% improvement over code for 3-Star certification, 20% for 4-Star, and 30% for 5-Star. Emerald Star homes must be net zero energy, which means these homes must consume the same or less energy than they produce via renewable energy in a year. These levels ensure Built Green certification carries meaning and acts a basis for incentives that benefit green builders.

Models are complicated; there is no doubt about that! Hopefully this post explains their purpose and how Built Green utilizes them. If you want to do a deep dive into the details of our modeling protocol, reach out to your third-party verifier for project specifics or to us for general information!

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Sometimes an old farmhouse can shelter a growing family for a long time and be ready to retire. In a special case, with a large lot, it can be reborn into a beautiful, sustainable, Built Green® 5-Star cottage development!

Juanita Farmhouse cottages, built by John Buchan Homes, accomplished just that. Comprising nine new cottages and a common house/barn that includes a guest apartment, it achieved both Built Green 5-Star and Built Green Communities certifications in 2018.

Built Green Highlights

Site and Water

The cottage development wraps beautifully around a central garden court, with generous porches and the common house helping create a sense of community. Many existing trees were carefully maintained and included in the final landscape, which features walkways, benches, and a terrace in front of the common house.

The common house includes a barn-like garage, a community room, and a kitchen off the large porch. The shared guest apartment is available to all community owners.

The site is provided with infiltration swales for roof water drainage that are integrated with native and drought-tolerant landscaping, utilizing all pervious surfaces except for part of the shared driveway. Indoor water use is reduced by the use of low flow fixtures and WaterSense toilets.

Energy Efficiency

The cottage homes are conventionally framed with enhanced insulation and ground-source heat pumps for top tier energy efficiency. Other energy efficiency features include:

Walls are blown-in blanket (BIBs) R 23

Windows are double-pane low-e argon units with .27 u value

Ground-source heating and cooling for best-in-class energy efficiency

Duct system pressure tested for very low leakage

Low-flow devices on sink and shower fixtures

ENERGY STAR appliances and 80 percent LED lighting

Because of the trees, not all of the homes have good solar access. The two cottages at the south east corner of the site are wired as “solar ready.”

Health and Indoor Air Quality

The homes emphasize simple interior finishes with low toxicity and excellent distributed ventilation for fresh air. The ground-source heat pump works through air circulation ducts that include automatic fresh air and a MERV 13 filter. There are no carpets—solid hardwood or tile flooring throughout—and all paint is low-VOC. A built-in shoe storage space and closet is found next to the front door. The homes are all-electric with no combustion fuels and a Bosch induction range in the kitchen.

Materials Efficiency

One of the stars of the show on this project is that every home has a hand-crafted kitchen island made of beautiful apple wood from one of the trees on the site that had to come down.

Interior finishes demonstrate a high level of commitment to non-toxic and environmentally friendly products. The builder took a lot of care to research and specify products. Interior caulks, adhesives, and finishes were checked for compliance with the Built Green VOC standards.

Comingled recycling of job site waste was handled at United Recycling, which maintains some of the better rates in the area—between 75 and 90 percent diversion.

We want to send out a big thank you to those who attended the Built Green Conference on September 13! What an invigorating, inspiring, thought-provoking day it was! With many builders and policymakers in attendance, as well as elected officials, consultants, vendors, architects, nonprofit staff, real estate agents, and students, we had a great opportunity to discuss and learn about issues impacting our region through a green building lens.

A key takeaway was the interconnectivity of many issues, as green building relates to the environment, healthy communities, workforce development, equity, and more. After all, Built Green supports green building because of the positive impacts it spurs for the planet and for people.

Keynote speaker Vien Truong began the day by relaying her inspiring story. Truong illuminated the link between environmental issues and the impacts they have, particularly on poorer communities. She also emphasized that everyone deserves healthy homes and communities, free of pollution, and that “being green isn’t partisan”—it’s the right thing to do. Her address left many moved and even prompted a question from the audience about whether she would run for president!

Following the keynote, the day was filled with educational sessions. Conference-goers had the opportunity to attend sessions from four different tracks: Greening Construction, Building Innovations, Advancing Policy, and Bettering Community. Session topics ranged from embodied carbon, prefab building, and deconstruction to displacement, a mayors’ panel, and how to get involved in code development. The excellent content variety ensured there was something for attendees from all sectors.

The day ended with a reception and awards ceremony. Some of the best projects from the past year were highlighted and Built Green supporters were recognized for their contributions to the program. Surprise awards included builder TC Legend Homes winning Project of the Year for their West Seattle Emerald Star home. Tadashi Shiga of Evergreen Certified and zHome residents Bryan Bell and Karin Weekly were also recognized as Built Green Pioneers for their advocacy. The Green Genius Awards were also announced, recognizing real estate agents and offices for their efforts in listing and selling green homes.

Throughout the day, conference attendees kept up conversation using the hashtag #builtgreen18 and connections were made both online and face-to-face. Several sessions were also livestreamed and can be found on our Facebook page.

We hope everyone who came to the conference learned something and walked away feeling inspired. See you next year!

What is net zero energy? Why is it important? How is it done? Real estate agents, architects, builders, consultants, policy makers, and others with interest in green building gathered at Green Canopy’s newest home in the Central District to find out on August 9.

If a building is net zero, that means it produces as much renewable energy as it uses over the course of a year. In this case, the home everyone gathered in for food, drinks, fun, and education has solar panels on the roof which, when combined with an efficient structure and appliances, mean the future residents will likely have no energy bills!

To learn more about the homes of the future—and of the present—watch this presentation to a packed crowd! Here’s what you’ll see:

Sam Lai discusses Green Canopy’s journey to building net zero and their theory of change.